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                                <h1 id="array-&#x5BF9;&#x8C61;">Array &#x5BF9;&#x8C61;</h1>
<h2 id="&#x6784;&#x9020;&#x51FD;&#x6570;">&#x6784;&#x9020;&#x51FD;&#x6570;</h2>
<p><code>Array</code>&#x662F; JavaScript &#x7684;&#x539F;&#x751F;&#x5BF9;&#x8C61;&#xFF0C;&#x540C;&#x65F6;&#x4E5F;&#x662F;&#x4E00;&#x4E2A;&#x6784;&#x9020;&#x51FD;&#x6570;&#xFF0C;&#x53EF;&#x4EE5;&#x7528;&#x5B83;&#x751F;&#x6210;&#x65B0;&#x7684;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">2</span>);
arr.length <span class="hljs-comment">// 2</span>
arr <span class="hljs-comment">// [ empty x 2 ]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>Array</code>&#x6784;&#x9020;&#x51FD;&#x6570;&#x7684;&#x53C2;&#x6570;<code>2</code>&#xFF0C;&#x8868;&#x793A;&#x751F;&#x6210;&#x4E00;&#x4E2A;&#x4E24;&#x4E2A;&#x6210;&#x5458;&#x7684;&#x6570;&#x7EC4;&#xFF0C;&#x6BCF;&#x4E2A;&#x4F4D;&#x7F6E;&#x90FD;&#x662F;&#x7A7A;&#x503C;&#x3002;</p>
<p>&#x5982;&#x679C;&#x6CA1;&#x6709;&#x4F7F;&#x7528;<code>new</code>&#xFF0C;&#x8FD0;&#x884C;&#x7ED3;&#x679C;&#x4E5F;&#x662F;&#x4E00;&#x6837;&#x7684;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">2</span>);
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-keyword">var</span> arr = <span class="hljs-built_in">Array</span>(<span class="hljs-number">2</span>);
</code></pre>
<p><code>Array</code>&#x6784;&#x9020;&#x51FD;&#x6570;&#x6709;&#x4E00;&#x4E2A;&#x5F88;&#x5927;&#x7684;&#x7F3A;&#x9677;&#xFF0C;&#x5C31;&#x662F;&#x4E0D;&#x540C;&#x7684;&#x53C2;&#x6570;&#xFF0C;&#x4F1A;&#x5BFC;&#x81F4;&#x5B83;&#x7684;&#x884C;&#x4E3A;&#x4E0D;&#x4E00;&#x81F4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-comment">// &#x65E0;&#x53C2;&#x6570;&#x65F6;&#xFF0C;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x7A7A;&#x6570;&#x7EC4;</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>() <span class="hljs-comment">// []</span>

<span class="hljs-comment">// &#x5355;&#x4E2A;&#x6B63;&#x6574;&#x6570;&#x53C2;&#x6570;&#xFF0C;&#x8868;&#x793A;&#x8FD4;&#x56DE;&#x7684;&#x65B0;&#x6570;&#x7EC4;&#x7684;&#x957F;&#x5EA6;</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">1</span>) <span class="hljs-comment">// [ empty ]</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">2</span>) <span class="hljs-comment">// [ empty x 2 ]</span>

<span class="hljs-comment">// &#x975E;&#x6B63;&#x6574;&#x6570;&#x7684;&#x6570;&#x503C;&#x4F5C;&#x4E3A;&#x53C2;&#x6570;&#xFF0C;&#x4F1A;&#x62A5;&#x9519;</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">3.2</span>) <span class="hljs-comment">// RangeError: Invalid array length</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">-3</span>) <span class="hljs-comment">// RangeError: Invalid array length</span>

<span class="hljs-comment">// &#x5355;&#x4E2A;&#x975E;&#x6570;&#x503C;&#xFF08;&#x6BD4;&#x5982;&#x5B57;&#x7B26;&#x4E32;&#x3001;&#x5E03;&#x5C14;&#x503C;&#x3001;&#x5BF9;&#x8C61;&#x7B49;&#xFF09;&#x4F5C;&#x4E3A;&#x53C2;&#x6570;&#xFF0C;</span>
<span class="hljs-comment">// &#x5219;&#x8BE5;&#x53C2;&#x6570;&#x662F;&#x8FD4;&#x56DE;&#x7684;&#x65B0;&#x6570;&#x7EC4;&#x7684;&#x6210;&#x5458;</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-string">&apos;abc&apos;</span>) <span class="hljs-comment">// [&apos;abc&apos;]</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>([<span class="hljs-number">1</span>]) <span class="hljs-comment">// [Array[1]]</span>

<span class="hljs-comment">// &#x591A;&#x53C2;&#x6570;&#x65F6;&#xFF0C;&#x6240;&#x6709;&#x53C2;&#x6570;&#x90FD;&#x662F;&#x8FD4;&#x56DE;&#x7684;&#x65B0;&#x6570;&#x7EC4;&#x7684;&#x6210;&#x5458;</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// [1, 2]</span>
<span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>) <span class="hljs-comment">// [&apos;a&apos;, &apos;b&apos;, &apos;c&apos;]</span>
</code></pre>
<p>&#x53EF;&#x4EE5;&#x770B;&#x5230;&#xFF0C;<code>Array</code>&#x4F5C;&#x4E3A;&#x6784;&#x9020;&#x51FD;&#x6570;&#xFF0C;&#x884C;&#x4E3A;&#x5F88;&#x4E0D;&#x4E00;&#x81F4;&#x3002;&#x56E0;&#x6B64;&#xFF0C;&#x4E0D;&#x5EFA;&#x8BAE;&#x4F7F;&#x7528;&#x5B83;&#x751F;&#x6210;&#x65B0;&#x6570;&#x7EC4;&#xFF0C;&#x76F4;&#x63A5;&#x4F7F;&#x7528;&#x6570;&#x7EC4;&#x5B57;&#x9762;&#x91CF;&#x662F;&#x66F4;&#x597D;&#x7684;&#x505A;&#x6CD5;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-comment">// bad</span>
<span class="hljs-keyword">var</span> arr = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);

<span class="hljs-comment">// good</span>
<span class="hljs-keyword">var</span> arr = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>];
</code></pre>
<p>&#x6CE8;&#x610F;&#xFF0C;&#x5982;&#x679C;&#x53C2;&#x6570;&#x662F;&#x4E00;&#x4E2A;&#x6B63;&#x6574;&#x6570;&#xFF0C;&#x8FD4;&#x56DE;&#x6570;&#x7EC4;&#x7684;&#x6210;&#x5458;&#x90FD;&#x662F;&#x7A7A;&#x4F4D;&#x3002;&#x867D;&#x7136;&#x8BFB;&#x53D6;&#x7684;&#x65F6;&#x5019;&#x8FD4;&#x56DE;<code>undefined</code>&#xFF0C;&#x4F46;&#x5B9E;&#x9645;&#x4E0A;&#x8BE5;&#x4F4D;&#x7F6E;&#x6CA1;&#x6709;&#x4EFB;&#x4F55;&#x503C;&#x3002;&#x867D;&#x7136;&#x53EF;&#x4EE5;&#x53D6;&#x5230;<code>length</code>&#x5C5E;&#x6027;&#xFF0C;&#x4F46;&#x662F;&#x53D6;&#x4E0D;&#x5230;&#x952E;&#x540D;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">3</span>);
<span class="hljs-keyword">var</span> b = [<span class="hljs-literal">undefined</span>, <span class="hljs-literal">undefined</span>, <span class="hljs-literal">undefined</span>];

a.length <span class="hljs-comment">// 3</span>
b.length <span class="hljs-comment">// 3</span>

a[<span class="hljs-number">0</span>] <span class="hljs-comment">// undefined</span>
b[<span class="hljs-number">0</span>] <span class="hljs-comment">// undefined</span>

<span class="hljs-number">0</span> <span class="hljs-keyword">in</span> a <span class="hljs-comment">// false</span>
<span class="hljs-number">0</span> <span class="hljs-keyword">in</span> b <span class="hljs-comment">// true</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>a</code>&#x662F;&#x4E00;&#x4E2A;&#x957F;&#x5EA6;&#x4E3A;3&#x7684;&#x7A7A;&#x6570;&#x7EC4;&#xFF0C;<code>b</code>&#x662F;&#x4E00;&#x4E2A;&#x4E09;&#x4E2A;&#x6210;&#x5458;&#x90FD;&#x662F;<code>undefined</code>&#x7684;&#x6570;&#x7EC4;&#x3002;&#x8BFB;&#x53D6;&#x952E;&#x503C;&#x7684;&#x65F6;&#x5019;&#xFF0C;<code>a</code>&#x548C;<code>b</code>&#x90FD;&#x8FD4;&#x56DE;<code>undefined</code>&#xFF0C;&#x4F46;&#x662F;<code>a</code>&#x7684;&#x952E;&#x4F4D;&#x90FD;&#x662F;&#x7A7A;&#x7684;&#xFF0C;<code>b</code>&#x7684;&#x952E;&#x4F4D;&#x662F;&#x6709;&#x503C;&#x7684;&#x3002;</p>
<h2 id="&#x9759;&#x6001;&#x65B9;&#x6CD5;">&#x9759;&#x6001;&#x65B9;&#x6CD5;</h2>
<h3 id="arrayisarray">Array.isArray()</h3>
<p><code>Array.isArray</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x5E03;&#x5C14;&#x503C;&#xFF0C;&#x8868;&#x793A;&#x53C2;&#x6570;&#x662F;&#x5426;&#x4E3A;&#x6570;&#x7EC4;&#x3002;&#x5B83;&#x53EF;&#x4EE5;&#x5F25;&#x8865;<code>typeof</code>&#x8FD0;&#x7B97;&#x7B26;&#x7684;&#x4E0D;&#x8DB3;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>];

<span class="hljs-keyword">typeof</span> arr <span class="hljs-comment">// &quot;object&quot;</span>
<span class="hljs-built_in">Array</span>.isArray(arr) <span class="hljs-comment">// true</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>typeof</code>&#x8FD0;&#x7B97;&#x7B26;&#x53EA;&#x80FD;&#x663E;&#x793A;&#x6570;&#x7EC4;&#x7684;&#x7C7B;&#x578B;&#x662F;<code>Object</code>&#xFF0C;&#x800C;<code>Array.isArray</code>&#x65B9;&#x6CD5;&#x53EF;&#x4EE5;&#x8BC6;&#x522B;&#x6570;&#x7EC4;&#x3002;</p>
<h2 id="&#x5B9E;&#x4F8B;&#x65B9;&#x6CD5;">&#x5B9E;&#x4F8B;&#x65B9;&#x6CD5;</h2>
<h3 id="valueof&#xFF0C;tostring">valueOf()&#xFF0C;toString()</h3>
<p><code>valueOf</code>&#x65B9;&#x6CD5;&#x662F;&#x4E00;&#x4E2A;&#x6240;&#x6709;&#x5BF9;&#x8C61;&#x90FD;&#x62E5;&#x6709;&#x7684;&#x65B9;&#x6CD5;&#xFF0C;&#x8868;&#x793A;&#x5BF9;&#x8BE5;&#x5BF9;&#x8C61;&#x6C42;&#x503C;&#x3002;&#x4E0D;&#x540C;&#x5BF9;&#x8C61;&#x7684;<code>valueOf</code>&#x65B9;&#x6CD5;&#x4E0D;&#x5C3D;&#x4E00;&#x81F4;&#xFF0C;&#x6570;&#x7EC4;&#x7684;<code>valueOf</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x6570;&#x7EC4;&#x672C;&#x8EAB;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>];
arr.valueOf() <span class="hljs-comment">// [1, 2, 3]</span>
</code></pre>
<p><code>toString</code>&#x65B9;&#x6CD5;&#x4E5F;&#x662F;&#x5BF9;&#x8C61;&#x7684;&#x901A;&#x7528;&#x65B9;&#x6CD5;&#xFF0C;&#x6570;&#x7EC4;&#x7684;<code>toString</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x6570;&#x7EC4;&#x7684;&#x5B57;&#x7B26;&#x4E32;&#x5F62;&#x5F0F;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>];
arr.toString() <span class="hljs-comment">// &quot;1,2,3&quot;</span>

<span class="hljs-keyword">var</span> arr = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, [<span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>]];
arr.toString() <span class="hljs-comment">// &quot;1,2,3,4,5,6&quot;</span>
</code></pre>
<h3 id="push&#xFF0C;pop">push()&#xFF0C;pop()</h3>
<p><code>push</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x5728;&#x6570;&#x7EC4;&#x7684;&#x672B;&#x7AEF;&#x6DFB;&#x52A0;&#x4E00;&#x4E2A;&#x6216;&#x591A;&#x4E2A;&#x5143;&#x7D20;&#xFF0C;&#x5E76;&#x8FD4;&#x56DE;&#x6DFB;&#x52A0;&#x65B0;&#x5143;&#x7D20;&#x540E;&#x7684;&#x6570;&#x7EC4;&#x957F;&#x5EA6;&#x3002;&#x6CE8;&#x610F;&#xFF0C;&#x8BE5;&#x65B9;&#x6CD5;&#x4F1A;&#x6539;&#x53D8;&#x539F;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [];

arr.push(<span class="hljs-number">1</span>) <span class="hljs-comment">// 1</span>
arr.push(<span class="hljs-string">&apos;a&apos;</span>) <span class="hljs-comment">// 2</span>
arr.push(<span class="hljs-literal">true</span>, {}) <span class="hljs-comment">// 4</span>
arr <span class="hljs-comment">// [1, &apos;a&apos;, true, {}]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4F7F;&#x7528;<code>push</code>&#x65B9;&#x6CD5;&#xFF0C;&#x5F80;&#x6570;&#x7EC4;&#x4E2D;&#x6DFB;&#x52A0;&#x4E86;&#x56DB;&#x4E2A;&#x6210;&#x5458;&#x3002;</p>
<p><code>pop</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x5220;&#x9664;&#x6570;&#x7EC4;&#x7684;&#x6700;&#x540E;&#x4E00;&#x4E2A;&#x5143;&#x7D20;&#xFF0C;&#x5E76;&#x8FD4;&#x56DE;&#x8BE5;&#x5143;&#x7D20;&#x3002;&#x6CE8;&#x610F;&#xFF0C;&#x8BE5;&#x65B9;&#x6CD5;&#x4F1A;&#x6539;&#x53D8;&#x539F;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];

arr.pop() <span class="hljs-comment">// &apos;c&apos;</span>
arr <span class="hljs-comment">// [&apos;a&apos;, &apos;b&apos;]</span>
</code></pre>
<p>&#x5BF9;&#x7A7A;&#x6570;&#x7EC4;&#x4F7F;&#x7528;<code>pop</code>&#x65B9;&#x6CD5;&#xFF0C;&#x4E0D;&#x4F1A;&#x62A5;&#x9519;&#xFF0C;&#x800C;&#x662F;&#x8FD4;&#x56DE;<code>undefined</code>&#x3002;</p>
<pre><code class="lang-javascript">[].pop() <span class="hljs-comment">// undefined</span>
</code></pre>
<p><code>push</code>&#x548C;<code>pop</code>&#x7ED3;&#x5408;&#x4F7F;&#x7528;&#xFF0C;&#x5C31;&#x6784;&#x6210;&#x4E86;&#x201C;&#x540E;&#x8FDB;&#x5148;&#x51FA;&#x201D;&#x7684;&#x6808;&#x7ED3;&#x6784;&#xFF08;stack&#xFF09;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [];
arr.push(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
arr.push(<span class="hljs-number">3</span>);
arr.pop();
arr <span class="hljs-comment">// [1, 2]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>3</code>&#x662F;&#x6700;&#x540E;&#x8FDB;&#x5165;&#x6570;&#x7EC4;&#x7684;&#xFF0C;&#x4F46;&#x662F;&#x6700;&#x65E9;&#x79BB;&#x5F00;&#x6570;&#x7EC4;&#x3002;</p>
<h3 id="shift&#xFF0C;unshift">shift()&#xFF0C;unshift()</h3>
<p><code>shift()</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x5220;&#x9664;&#x6570;&#x7EC4;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x5143;&#x7D20;&#xFF0C;&#x5E76;&#x8FD4;&#x56DE;&#x8BE5;&#x5143;&#x7D20;&#x3002;&#x6CE8;&#x610F;&#xFF0C;&#x8BE5;&#x65B9;&#x6CD5;&#x4F1A;&#x6539;&#x53D8;&#x539F;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];

a.shift() <span class="hljs-comment">// &apos;a&apos;</span>
a <span class="hljs-comment">// [&apos;b&apos;, &apos;c&apos;]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x4F7F;&#x7528;<code>shift()</code>&#x65B9;&#x6CD5;&#x4EE5;&#x540E;&#xFF0C;&#x539F;&#x6570;&#x7EC4;&#x5C31;&#x53D8;&#x4E86;&#x3002;</p>
<p><code>shift()</code>&#x65B9;&#x6CD5;&#x53EF;&#x4EE5;&#x904D;&#x5386;&#x5E76;&#x6E05;&#x7A7A;&#x4E00;&#x4E2A;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> list = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>];
<span class="hljs-keyword">var</span> item;

<span class="hljs-keyword">while</span> (item = list.shift()) {
  <span class="hljs-built_in">console</span>.log(item);
}

list <span class="hljs-comment">// []</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x901A;&#x8FC7;<code>list.shift()</code>&#x65B9;&#x6CD5;&#x6BCF;&#x6B21;&#x53D6;&#x51FA;&#x4E00;&#x4E2A;&#x5143;&#x7D20;&#xFF0C;&#x4ECE;&#x800C;&#x904D;&#x5386;&#x6570;&#x7EC4;&#x3002;&#x5B83;&#x7684;&#x524D;&#x63D0;&#x662F;&#x6570;&#x7EC4;&#x5143;&#x7D20;&#x4E0D;&#x80FD;&#x662F;<code>0</code>&#x6216;&#x4EFB;&#x4F55;&#x5E03;&#x5C14;&#x503C;&#x7B49;&#x4E8E;<code>false</code>&#x7684;&#x5143;&#x7D20;&#xFF0C;&#x56E0;&#x6B64;&#x8FD9;&#x6837;&#x7684;&#x904D;&#x5386;&#x4E0D;&#x662F;&#x5F88;&#x53EF;&#x9760;&#x3002;</p>
<p><code>push()</code>&#x548C;<code>shift()</code>&#x7ED3;&#x5408;&#x4F7F;&#x7528;&#xFF0C;&#x5C31;&#x6784;&#x6210;&#x4E86;&#x201C;&#x5148;&#x8FDB;&#x5148;&#x51FA;&#x201D;&#x7684;&#x961F;&#x5217;&#x7ED3;&#x6784;&#xFF08;queue&#xFF09;&#x3002;</p>
<p><code>unshift()</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x5728;&#x6570;&#x7EC4;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x4F4D;&#x7F6E;&#x6DFB;&#x52A0;&#x5143;&#x7D20;&#xFF0C;&#x5E76;&#x8FD4;&#x56DE;&#x6DFB;&#x52A0;&#x65B0;&#x5143;&#x7D20;&#x540E;&#x7684;&#x6570;&#x7EC4;&#x957F;&#x5EA6;&#x3002;&#x6CE8;&#x610F;&#xFF0C;&#x8BE5;&#x65B9;&#x6CD5;&#x4F1A;&#x6539;&#x53D8;&#x539F;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];

a.unshift(<span class="hljs-string">&apos;x&apos;</span>); <span class="hljs-comment">// 4</span>
a <span class="hljs-comment">// [&apos;x&apos;, &apos;a&apos;, &apos;b&apos;, &apos;c&apos;]</span>
</code></pre>
<p><code>unshift()</code>&#x65B9;&#x6CD5;&#x53EF;&#x4EE5;&#x63A5;&#x53D7;&#x591A;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x8FD9;&#x4E9B;&#x53C2;&#x6570;&#x90FD;&#x4F1A;&#x6DFB;&#x52A0;&#x5230;&#x76EE;&#x6807;&#x6570;&#x7EC4;&#x5934;&#x90E8;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [ <span class="hljs-string">&apos;c&apos;</span>, <span class="hljs-string">&apos;d&apos;</span> ];
arr.unshift(<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>) <span class="hljs-comment">// 4</span>
arr <span class="hljs-comment">// [ &apos;a&apos;, &apos;b&apos;, &apos;c&apos;, &apos;d&apos; ]</span>
</code></pre>
<h3 id="join">join()</h3>
<p><code>join()</code>&#x65B9;&#x6CD5;&#x4EE5;&#x6307;&#x5B9A;&#x53C2;&#x6570;&#x4F5C;&#x4E3A;&#x5206;&#x9694;&#x7B26;&#xFF0C;&#x5C06;&#x6240;&#x6709;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x8FDE;&#x63A5;&#x4E3A;&#x4E00;&#x4E2A;&#x5B57;&#x7B26;&#x4E32;&#x8FD4;&#x56DE;&#x3002;&#x5982;&#x679C;&#x4E0D;&#x63D0;&#x4F9B;&#x53C2;&#x6570;&#xFF0C;&#x9ED8;&#x8BA4;&#x7528;&#x9017;&#x53F7;&#x5206;&#x9694;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>];

a.join(<span class="hljs-string">&apos; &apos;</span>) <span class="hljs-comment">// &apos;1 2 3 4&apos;</span>
a.join(<span class="hljs-string">&apos; | &apos;</span>) <span class="hljs-comment">// &quot;1 | 2 | 3 | 4&quot;</span>
a.join() <span class="hljs-comment">// &quot;1,2,3,4&quot;</span>
</code></pre>
<p>&#x5982;&#x679C;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x662F;<code>undefined</code>&#x6216;<code>null</code>&#x6216;&#x7A7A;&#x4F4D;&#xFF0C;&#x4F1A;&#x88AB;&#x8F6C;&#x6210;&#x7A7A;&#x5B57;&#x7B26;&#x4E32;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-literal">undefined</span>, <span class="hljs-literal">null</span>].join(<span class="hljs-string">&apos;#&apos;</span>)
<span class="hljs-comment">// &apos;#&apos;</span>

[<span class="hljs-string">&apos;a&apos;</span>,, <span class="hljs-string">&apos;b&apos;</span>].join(<span class="hljs-string">&apos;-&apos;</span>)
<span class="hljs-comment">// &apos;a--b&apos;</span>
</code></pre>
<p>&#x901A;&#x8FC7;<code>call</code>&#x65B9;&#x6CD5;&#xFF0C;&#x8FD9;&#x4E2A;&#x65B9;&#x6CD5;&#x4E5F;&#x53EF;&#x4EE5;&#x7528;&#x4E8E;&#x5B57;&#x7B26;&#x4E32;&#x6216;&#x7C7B;&#x4F3C;&#x6570;&#x7EC4;&#x7684;&#x5BF9;&#x8C61;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Array</span>.prototype.join.call(<span class="hljs-string">&apos;hello&apos;</span>, <span class="hljs-string">&apos;-&apos;</span>)
<span class="hljs-comment">// &quot;h-e-l-l-o&quot;</span>

<span class="hljs-keyword">var</span> obj = { <span class="hljs-number">0</span>: <span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-number">1</span>: <span class="hljs-string">&apos;b&apos;</span>, length: <span class="hljs-number">2</span> };
<span class="hljs-built_in">Array</span>.prototype.join.call(obj, <span class="hljs-string">&apos;-&apos;</span>)
<span class="hljs-comment">// &apos;a-b&apos;</span>
</code></pre>
<h3 id="concat">concat()</h3>
<p><code>concat</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x591A;&#x4E2A;&#x6570;&#x7EC4;&#x7684;&#x5408;&#x5E76;&#x3002;&#x5B83;&#x5C06;&#x65B0;&#x6570;&#x7EC4;&#x7684;&#x6210;&#x5458;&#xFF0C;&#x6DFB;&#x52A0;&#x5230;&#x539F;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x7684;&#x540E;&#x90E8;&#xFF0C;&#x7136;&#x540E;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x65B0;&#x6570;&#x7EC4;&#xFF0C;&#x539F;&#x6570;&#x7EC4;&#x4E0D;&#x53D8;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-string">&apos;hello&apos;</span>].concat([<span class="hljs-string">&apos;world&apos;</span>])
<span class="hljs-comment">// [&quot;hello&quot;, &quot;world&quot;]</span>

[<span class="hljs-string">&apos;hello&apos;</span>].concat([<span class="hljs-string">&apos;world&apos;</span>], [<span class="hljs-string">&apos;!&apos;</span>])
<span class="hljs-comment">// [&quot;hello&quot;, &quot;world&quot;, &quot;!&quot;]</span>

[].concat({a: <span class="hljs-number">1</span>}, {b: <span class="hljs-number">2</span>})
<span class="hljs-comment">// [{ a: 1 }, { b: 2 }]</span>

[<span class="hljs-number">2</span>].concat({a: <span class="hljs-number">1</span>})
<span class="hljs-comment">// [2, {a: 1}]</span>
</code></pre>
<p>&#x9664;&#x4E86;&#x6570;&#x7EC4;&#x4F5C;&#x4E3A;&#x53C2;&#x6570;&#xFF0C;<code>concat</code>&#x4E5F;&#x63A5;&#x53D7;&#x5176;&#x4ED6;&#x7C7B;&#x578B;&#x7684;&#x503C;&#x4F5C;&#x4E3A;&#x53C2;&#x6570;&#xFF0C;&#x6DFB;&#x52A0;&#x5230;&#x76EE;&#x6807;&#x6570;&#x7EC4;&#x5C3E;&#x90E8;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>].concat(<span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>)
<span class="hljs-comment">// [1, 2, 3, 4, 5, 6]</span>
</code></pre>
<p>&#x5982;&#x679C;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x5305;&#x62EC;&#x5BF9;&#x8C61;&#xFF0C;<code>concat</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x5F53;&#x524D;&#x6570;&#x7EC4;&#x7684;&#x4E00;&#x4E2A;&#x6D45;&#x62F7;&#x8D1D;&#x3002;&#x6240;&#x8C13;&#x201C;&#x6D45;&#x62F7;&#x8D1D;&#x201D;&#xFF0C;&#x6307;&#x7684;&#x662F;&#x65B0;&#x6570;&#x7EC4;&#x62F7;&#x8D1D;&#x7684;&#x662F;&#x5BF9;&#x8C61;&#x7684;&#x5F15;&#x7528;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> obj = { a: <span class="hljs-number">1</span> };
<span class="hljs-keyword">var</span> oldArray = [obj];

<span class="hljs-keyword">var</span> newArray = oldArray.concat();

obj.a = <span class="hljs-number">2</span>;
newArray[<span class="hljs-number">0</span>].a <span class="hljs-comment">// 2</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x539F;&#x6570;&#x7EC4;&#x5305;&#x542B;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#xFF0C;<code>concat</code>&#x65B9;&#x6CD5;&#x751F;&#x6210;&#x7684;&#x65B0;&#x6570;&#x7EC4;&#x5305;&#x542B;&#x8FD9;&#x4E2A;&#x5BF9;&#x8C61;&#x7684;&#x5F15;&#x7528;&#x3002;&#x6240;&#x4EE5;&#xFF0C;&#x6539;&#x53D8;&#x539F;&#x5BF9;&#x8C61;&#x4EE5;&#x540E;&#xFF0C;&#x65B0;&#x6570;&#x7EC4;&#x8DDF;&#x7740;&#x6539;&#x53D8;&#x3002;</p>
<h3 id="reverse">reverse()</h3>
<p><code>reverse</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x98A0;&#x5012;&#x6392;&#x5217;&#x6570;&#x7EC4;&#x5143;&#x7D20;&#xFF0C;&#x8FD4;&#x56DE;&#x6539;&#x53D8;&#x540E;&#x7684;&#x6570;&#x7EC4;&#x3002;&#x6CE8;&#x610F;&#xFF0C;&#x8BE5;&#x65B9;&#x6CD5;&#x5C06;&#x6539;&#x53D8;&#x539F;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];

a.reverse() <span class="hljs-comment">// [&quot;c&quot;, &quot;b&quot;, &quot;a&quot;]</span>
a <span class="hljs-comment">// [&quot;c&quot;, &quot;b&quot;, &quot;a&quot;]</span>
</code></pre>
<h3 id="slice">slice()</h3>
<p><code>slice</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x63D0;&#x53D6;&#x76EE;&#x6807;&#x6570;&#x7EC4;&#x7684;&#x4E00;&#x90E8;&#x5206;&#xFF0C;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x65B0;&#x6570;&#x7EC4;&#xFF0C;&#x539F;&#x6570;&#x7EC4;&#x4E0D;&#x53D8;&#x3002;</p>
<pre><code class="lang-javascript">arr.slice(start, end);
</code></pre>
<p>&#x5B83;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x4E3A;&#x8D77;&#x59CB;&#x4F4D;&#x7F6E;&#xFF08;&#x4ECE;0&#x5F00;&#x59CB;&#xFF09;&#xFF0C;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x4E3A;&#x7EC8;&#x6B62;&#x4F4D;&#x7F6E;&#xFF08;&#x4F46;&#x8BE5;&#x4F4D;&#x7F6E;&#x7684;&#x5143;&#x7D20;&#x672C;&#x8EAB;&#x4E0D;&#x5305;&#x62EC;&#x5728;&#x5185;&#xFF09;&#x3002;&#x5982;&#x679C;&#x7701;&#x7565;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x5219;&#x4E00;&#x76F4;&#x8FD4;&#x56DE;&#x5230;&#x539F;&#x6570;&#x7EC4;&#x7684;&#x6700;&#x540E;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];

a.slice(<span class="hljs-number">0</span>) <span class="hljs-comment">// [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;]</span>
a.slice(<span class="hljs-number">1</span>) <span class="hljs-comment">// [&quot;b&quot;, &quot;c&quot;]</span>
a.slice(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// [&quot;b&quot;]</span>
a.slice(<span class="hljs-number">2</span>, <span class="hljs-number">6</span>) <span class="hljs-comment">// [&quot;c&quot;]</span>
a.slice() <span class="hljs-comment">// [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x6700;&#x540E;&#x4E00;&#x4E2A;&#x4F8B;&#x5B50;<code>slice</code>&#x6CA1;&#x6709;&#x53C2;&#x6570;&#xFF0C;&#x5B9E;&#x9645;&#x4E0A;&#x7B49;&#x4E8E;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x539F;&#x6570;&#x7EC4;&#x7684;&#x62F7;&#x8D1D;&#x3002;</p>
<p>&#x5982;&#x679C;<code>slice</code>&#x65B9;&#x6CD5;&#x7684;&#x53C2;&#x6570;&#x662F;&#x8D1F;&#x6570;&#xFF0C;&#x5219;&#x8868;&#x793A;&#x5012;&#x6570;&#x8BA1;&#x7B97;&#x7684;&#x4F4D;&#x7F6E;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];
a.slice(<span class="hljs-number">-2</span>) <span class="hljs-comment">// [&quot;b&quot;, &quot;c&quot;]</span>
a.slice(<span class="hljs-number">-2</span>, <span class="hljs-number">-1</span>) <span class="hljs-comment">// [&quot;b&quot;]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>-2</code>&#x8868;&#x793A;&#x5012;&#x6570;&#x8BA1;&#x7B97;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x4F4D;&#x7F6E;&#xFF0C;<code>-1</code>&#x8868;&#x793A;&#x5012;&#x6570;&#x8BA1;&#x7B97;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x4F4D;&#x7F6E;&#x3002;</p>
<p>&#x5982;&#x679C;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x5927;&#x4E8E;&#x7B49;&#x4E8E;&#x6570;&#x7EC4;&#x957F;&#x5EA6;&#xFF0C;&#x6216;&#x8005;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x5C0F;&#x4E8E;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x5219;&#x8FD4;&#x56DE;&#x7A7A;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];
a.slice(<span class="hljs-number">4</span>) <span class="hljs-comment">// []</span>
a.slice(<span class="hljs-number">2</span>, <span class="hljs-number">1</span>) <span class="hljs-comment">// []</span>
</code></pre>
<p><code>slice</code>&#x65B9;&#x6CD5;&#x7684;&#x4E00;&#x4E2A;&#x91CD;&#x8981;&#x5E94;&#x7528;&#xFF0C;&#x662F;&#x5C06;&#x7C7B;&#x4F3C;&#x6570;&#x7EC4;&#x7684;&#x5BF9;&#x8C61;&#x8F6C;&#x4E3A;&#x771F;&#x6B63;&#x7684;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-built_in">Array</span>.prototype.slice.call({ <span class="hljs-number">0</span>: <span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-number">1</span>: <span class="hljs-string">&apos;b&apos;</span>, length: <span class="hljs-number">2</span> })
<span class="hljs-comment">// [&apos;a&apos;, &apos;b&apos;]</span>

<span class="hljs-built_in">Array</span>.prototype.slice.call(<span class="hljs-built_in">document</span>.querySelectorAll(<span class="hljs-string">&quot;div&quot;</span>));
<span class="hljs-built_in">Array</span>.prototype.slice.call(<span class="hljs-built_in">arguments</span>);
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x7684;&#x53C2;&#x6570;&#x90FD;&#x4E0D;&#x662F;&#x6570;&#x7EC4;&#xFF0C;&#x4F46;&#x662F;&#x901A;&#x8FC7;<code>call</code>&#x65B9;&#x6CD5;&#xFF0C;&#x5728;&#x5B83;&#x4EEC;&#x4E0A;&#x9762;&#x8C03;&#x7528;<code>slice</code>&#x65B9;&#x6CD5;&#xFF0C;&#x5C31;&#x53EF;&#x4EE5;&#x628A;&#x5B83;&#x4EEC;&#x8F6C;&#x4E3A;&#x771F;&#x6B63;&#x7684;&#x6570;&#x7EC4;&#x3002;</p>
<h3 id="splice">splice()</h3>
<p><code>splice</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x5220;&#x9664;&#x539F;&#x6570;&#x7EC4;&#x7684;&#x4E00;&#x90E8;&#x5206;&#x6210;&#x5458;&#xFF0C;&#x5E76;&#x53EF;&#x4EE5;&#x5728;&#x5220;&#x9664;&#x7684;&#x4F4D;&#x7F6E;&#x6DFB;&#x52A0;&#x65B0;&#x7684;&#x6570;&#x7EC4;&#x6210;&#x5458;&#xFF0C;&#x8FD4;&#x56DE;&#x503C;&#x662F;&#x88AB;&#x5220;&#x9664;&#x7684;&#x5143;&#x7D20;&#x3002;&#x6CE8;&#x610F;&#xFF0C;&#x8BE5;&#x65B9;&#x6CD5;&#x4F1A;&#x6539;&#x53D8;&#x539F;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript">arr.splice(start, count, addElement1, addElement2, ...);
</code></pre>
<p><code>splice</code>&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x662F;&#x5220;&#x9664;&#x7684;&#x8D77;&#x59CB;&#x4F4D;&#x7F6E;&#xFF08;&#x4ECE;0&#x5F00;&#x59CB;&#xFF09;&#xFF0C;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x662F;&#x88AB;&#x5220;&#x9664;&#x7684;&#x5143;&#x7D20;&#x4E2A;&#x6570;&#x3002;&#x5982;&#x679C;&#x540E;&#x9762;&#x8FD8;&#x6709;&#x66F4;&#x591A;&#x7684;&#x53C2;&#x6570;&#xFF0C;&#x5219;&#x8868;&#x793A;&#x8FD9;&#x4E9B;&#x5C31;&#x662F;&#x8981;&#x88AB;&#x63D2;&#x5165;&#x6570;&#x7EC4;&#x7684;&#x65B0;&#x5143;&#x7D20;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>, <span class="hljs-string">&apos;d&apos;</span>, <span class="hljs-string">&apos;e&apos;</span>, <span class="hljs-string">&apos;f&apos;</span>];
a.splice(<span class="hljs-number">4</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// [&quot;e&quot;, &quot;f&quot;]</span>
a <span class="hljs-comment">// [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;, &quot;d&quot;]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4ECE;&#x539F;&#x6570;&#x7EC4;4&#x53F7;&#x4F4D;&#x7F6E;&#xFF0C;&#x5220;&#x9664;&#x4E86;&#x4E24;&#x4E2A;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>, <span class="hljs-string">&apos;d&apos;</span>, <span class="hljs-string">&apos;e&apos;</span>, <span class="hljs-string">&apos;f&apos;</span>];
a.splice(<span class="hljs-number">4</span>, <span class="hljs-number">2</span>, <span class="hljs-number">1</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// [&quot;e&quot;, &quot;f&quot;]</span>
a <span class="hljs-comment">// [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;, &quot;d&quot;, 1, 2]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x9664;&#x4E86;&#x5220;&#x9664;&#x6210;&#x5458;&#xFF0C;&#x8FD8;&#x63D2;&#x5165;&#x4E86;&#x4E24;&#x4E2A;&#x65B0;&#x6210;&#x5458;&#x3002;</p>
<p>&#x8D77;&#x59CB;&#x4F4D;&#x7F6E;&#x5982;&#x679C;&#x662F;&#x8D1F;&#x6570;&#xFF0C;&#x5C31;&#x8868;&#x793A;&#x4ECE;&#x5012;&#x6570;&#x4F4D;&#x7F6E;&#x5F00;&#x59CB;&#x5220;&#x9664;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>, <span class="hljs-string">&apos;d&apos;</span>, <span class="hljs-string">&apos;e&apos;</span>, <span class="hljs-string">&apos;f&apos;</span>];
a.splice(<span class="hljs-number">-4</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// [&quot;c&quot;, &quot;d&quot;]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x8868;&#x793A;&#xFF0C;&#x4ECE;&#x5012;&#x6570;&#x7B2C;&#x56DB;&#x4E2A;&#x4F4D;&#x7F6E;<code>c</code>&#x5F00;&#x59CB;&#x5220;&#x9664;&#x4E24;&#x4E2A;&#x6210;&#x5458;&#x3002;</p>
<p>&#x5982;&#x679C;&#x53EA;&#x662F;&#x5355;&#x7EAF;&#x5730;&#x63D2;&#x5165;&#x5143;&#x7D20;&#xFF0C;<code>splice</code>&#x65B9;&#x6CD5;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x53EF;&#x4EE5;&#x8BBE;&#x4E3A;<code>0</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-number">1</span>, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>];

a.splice(<span class="hljs-number">1</span>, <span class="hljs-number">0</span>, <span class="hljs-number">2</span>) <span class="hljs-comment">// []</span>
a <span class="hljs-comment">// [1, 2, 1, 1]</span>
</code></pre>
<p>&#x5982;&#x679C;&#x53EA;&#x63D0;&#x4F9B;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x7B49;&#x540C;&#x4E8E;&#x5C06;&#x539F;&#x6570;&#x7EC4;&#x5728;&#x6307;&#x5B9A;&#x4F4D;&#x7F6E;&#x62C6;&#x5206;&#x6210;&#x4E24;&#x4E2A;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>];
a.splice(<span class="hljs-number">2</span>) <span class="hljs-comment">// [3, 4]</span>
a <span class="hljs-comment">// [1, 2]</span>
</code></pre>
<h3 id="sort">sort()</h3>
<p><code>sort</code>&#x65B9;&#x6CD5;&#x5BF9;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x8FDB;&#x884C;&#x6392;&#x5E8F;&#xFF0C;&#x9ED8;&#x8BA4;&#x662F;&#x6309;&#x7167;&#x5B57;&#x5178;&#x987A;&#x5E8F;&#x6392;&#x5E8F;&#x3002;&#x6392;&#x5E8F;&#x540E;&#xFF0C;&#x539F;&#x6570;&#x7EC4;&#x5C06;&#x88AB;&#x6539;&#x53D8;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-string">&apos;d&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;a&apos;</span>].sort()
<span class="hljs-comment">// [&apos;a&apos;, &apos;b&apos;, &apos;c&apos;, &apos;d&apos;]</span>

[<span class="hljs-number">4</span>, <span class="hljs-number">3</span>, <span class="hljs-number">2</span>, <span class="hljs-number">1</span>].sort()
<span class="hljs-comment">// [1, 2, 3, 4]</span>

[<span class="hljs-number">11</span>, <span class="hljs-number">101</span>].sort()
<span class="hljs-comment">// [101, 11]</span>

[<span class="hljs-number">10111</span>, <span class="hljs-number">1101</span>, <span class="hljs-number">111</span>].sort()
<span class="hljs-comment">// [10111, 1101, 111]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x7684;&#x6700;&#x540E;&#x4E24;&#x4E2A;&#x4F8B;&#x5B50;&#xFF0C;&#x9700;&#x8981;&#x7279;&#x6B8A;&#x6CE8;&#x610F;&#x3002;<code>sort</code>&#x65B9;&#x6CD5;&#x4E0D;&#x662F;&#x6309;&#x7167;&#x5927;&#x5C0F;&#x6392;&#x5E8F;&#xFF0C;&#x800C;&#x662F;&#x6309;&#x7167;&#x5B57;&#x5178;&#x987A;&#x5E8F;&#x3002;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#xFF0C;&#x6570;&#x503C;&#x4F1A;&#x88AB;&#x5148;&#x8F6C;&#x6210;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x518D;&#x6309;&#x7167;&#x5B57;&#x5178;&#x987A;&#x5E8F;&#x8FDB;&#x884C;&#x6BD4;&#x8F83;&#xFF0C;&#x6240;&#x4EE5;<code>101</code>&#x6392;&#x5728;<code>11</code>&#x7684;&#x524D;&#x9762;&#x3002;</p>
<p>&#x5982;&#x679C;&#x60F3;&#x8BA9;<code>sort</code>&#x65B9;&#x6CD5;&#x6309;&#x7167;&#x81EA;&#x5B9A;&#x4E49;&#x65B9;&#x5F0F;&#x6392;&#x5E8F;&#xFF0C;&#x53EF;&#x4EE5;&#x4F20;&#x5165;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#x4F5C;&#x4E3A;&#x53C2;&#x6570;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-number">10111</span>, <span class="hljs-number">1101</span>, <span class="hljs-number">111</span>].sort(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">a, b</span>) </span>{
  <span class="hljs-keyword">return</span> a - b;
})
<span class="hljs-comment">// [111, 1101, 10111]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>sort</code>&#x7684;&#x53C2;&#x6570;&#x51FD;&#x6570;&#x672C;&#x8EAB;&#x63A5;&#x53D7;&#x4E24;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x8868;&#x793A;&#x8FDB;&#x884C;&#x6BD4;&#x8F83;&#x7684;&#x4E24;&#x4E2A;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x3002;&#x5982;&#x679C;&#x8BE5;&#x51FD;&#x6570;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x5927;&#x4E8E;<code>0</code>&#xFF0C;&#x8868;&#x793A;&#x7B2C;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#x6392;&#x5728;&#x7B2C;&#x4E8C;&#x4E2A;&#x6210;&#x5458;&#x540E;&#x9762;&#xFF1B;&#x5176;&#x4ED6;&#x60C5;&#x51B5;&#x4E0B;&#xFF0C;&#x90FD;&#x662F;&#x7B2C;&#x4E00;&#x4E2A;&#x5143;&#x7D20;&#x6392;&#x5728;&#x7B2C;&#x4E8C;&#x4E2A;&#x5143;&#x7D20;&#x524D;&#x9762;&#x3002;</p>
<pre><code class="lang-javascript">[
  { name: <span class="hljs-string">&quot;&#x5F20;&#x4E09;&quot;</span>, age: <span class="hljs-number">30</span> },
  { name: <span class="hljs-string">&quot;&#x674E;&#x56DB;&quot;</span>, age: <span class="hljs-number">24</span> },
  { name: <span class="hljs-string">&quot;&#x738B;&#x4E94;&quot;</span>, age: <span class="hljs-number">28</span>  }
].sort(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">o1, o2</span>) </span>{
  <span class="hljs-keyword">return</span> o1.age - o2.age;
})
<span class="hljs-comment">// [</span>
<span class="hljs-comment">//   { name: &quot;&#x674E;&#x56DB;&quot;, age: 24 },</span>
<span class="hljs-comment">//   { name: &quot;&#x738B;&#x4E94;&quot;, age: 28  },</span>
<span class="hljs-comment">//   { name: &quot;&#x5F20;&#x4E09;&quot;, age: 30 }</span>
<span class="hljs-comment">// ]</span>
</code></pre>
<h3 id="map">map()</h3>
<p><code>map</code>&#x65B9;&#x6CD5;&#x5C06;&#x6570;&#x7EC4;&#x7684;&#x6240;&#x6709;&#x6210;&#x5458;&#x4F9D;&#x6B21;&#x4F20;&#x5165;&#x53C2;&#x6570;&#x51FD;&#x6570;&#xFF0C;&#x7136;&#x540E;&#x628A;&#x6BCF;&#x4E00;&#x6B21;&#x7684;&#x6267;&#x884C;&#x7ED3;&#x679C;&#x7EC4;&#x6210;&#x4E00;&#x4E2A;&#x65B0;&#x6570;&#x7EC4;&#x8FD4;&#x56DE;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> numbers = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>];

numbers.map(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">n</span>) </span>{
  <span class="hljs-keyword">return</span> n + <span class="hljs-number">1</span>;
});
<span class="hljs-comment">// [2, 3, 4]</span>

numbers
<span class="hljs-comment">// [1, 2, 3]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>numbers</code>&#x6570;&#x7EC4;&#x7684;&#x6240;&#x6709;&#x6210;&#x5458;&#x4F9D;&#x6B21;&#x6267;&#x884C;&#x53C2;&#x6570;&#x51FD;&#x6570;&#xFF0C;&#x8FD0;&#x884C;&#x7ED3;&#x679C;&#x7EC4;&#x6210;&#x4E00;&#x4E2A;&#x65B0;&#x6570;&#x7EC4;&#x8FD4;&#x56DE;&#xFF0C;&#x539F;&#x6570;&#x7EC4;&#x6CA1;&#x6709;&#x53D8;&#x5316;&#x3002;</p>
<p><code>map</code>&#x65B9;&#x6CD5;&#x63A5;&#x53D7;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#x4F5C;&#x4E3A;&#x53C2;&#x6570;&#x3002;&#x8BE5;&#x51FD;&#x6570;&#x8C03;&#x7528;&#x65F6;&#xFF0C;<code>map</code>&#x65B9;&#x6CD5;&#x5411;&#x5B83;&#x4F20;&#x5165;&#x4E09;&#x4E2A;&#x53C2;&#x6570;&#xFF1A;&#x5F53;&#x524D;&#x6210;&#x5458;&#x3001;&#x5F53;&#x524D;&#x4F4D;&#x7F6E;&#x548C;&#x6570;&#x7EC4;&#x672C;&#x8EAB;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>].map(<span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params">elem, index, arr</span>) </span>{
  <span class="hljs-keyword">return</span> elem * index;
});
<span class="hljs-comment">// [0, 2, 6]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>map</code>&#x65B9;&#x6CD5;&#x7684;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x6709;&#x4E09;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;<code>elem</code>&#x4E3A;&#x5F53;&#x524D;&#x6210;&#x5458;&#x7684;&#x503C;&#xFF0C;<code>index</code>&#x4E3A;&#x5F53;&#x524D;&#x6210;&#x5458;&#x7684;&#x4F4D;&#x7F6E;&#xFF0C;<code>arr</code>&#x4E3A;&#x539F;&#x6570;&#x7EC4;&#xFF08;<code>[1, 2, 3]</code>&#xFF09;&#x3002;</p>
<p><code>map</code>&#x65B9;&#x6CD5;&#x8FD8;&#x53EF;&#x4EE5;&#x63A5;&#x53D7;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x7528;&#x6765;&#x7ED1;&#x5B9A;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x5185;&#x90E8;&#x7684;<code>this</code>&#x53D8;&#x91CF;&#xFF08;&#x8BE6;&#x89C1;&#x300A;this &#x53D8;&#x91CF;&#x300B;&#x4E00;&#x7AE0;&#xFF09;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];

[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>].map(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">e</span>) </span>{
  <span class="hljs-keyword">return</span> <span class="hljs-keyword">this</span>[e];
}, arr)
<span class="hljs-comment">// [&apos;b&apos;, &apos;c&apos;]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x901A;&#x8FC7;<code>map</code>&#x65B9;&#x6CD5;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x5C06;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x5185;&#x90E8;&#x7684;<code>this</code>&#x5BF9;&#x8C61;&#xFF0C;&#x6307;&#x5411;<code>arr</code>&#x6570;&#x7EC4;&#x3002;</p>
<p>&#x5982;&#x679C;&#x6570;&#x7EC4;&#x6709;&#x7A7A;&#x4F4D;&#xFF0C;<code>map</code>&#x65B9;&#x6CD5;&#x7684;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x5728;&#x8FD9;&#x4E2A;&#x4F4D;&#x7F6E;&#x4E0D;&#x4F1A;&#x6267;&#x884C;&#xFF0C;&#x4F1A;&#x8DF3;&#x8FC7;&#x6570;&#x7EC4;&#x7684;&#x7A7A;&#x4F4D;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> f = <span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">n</span>) </span>{ <span class="hljs-keyword">return</span> <span class="hljs-string">&apos;a&apos;</span> };

[<span class="hljs-number">1</span>, <span class="hljs-literal">undefined</span>, <span class="hljs-number">2</span>].map(f) <span class="hljs-comment">// [&quot;a&quot;, &quot;a&quot;, &quot;a&quot;]</span>
[<span class="hljs-number">1</span>, <span class="hljs-literal">null</span>, <span class="hljs-number">2</span>].map(f) <span class="hljs-comment">// [&quot;a&quot;, &quot;a&quot;, &quot;a&quot;]</span>
[<span class="hljs-number">1</span>, , <span class="hljs-number">2</span>].map(f) <span class="hljs-comment">// [&quot;a&quot;, , &quot;a&quot;]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>map</code>&#x65B9;&#x6CD5;&#x4E0D;&#x4F1A;&#x8DF3;&#x8FC7;<code>undefined</code>&#x548C;<code>null</code>&#xFF0C;&#x4F46;&#x662F;&#x4F1A;&#x8DF3;&#x8FC7;&#x7A7A;&#x4F4D;&#x3002;</p>
<h3 id="foreach">forEach()</h3>
<p><code>forEach</code>&#x65B9;&#x6CD5;&#x4E0E;<code>map</code>&#x65B9;&#x6CD5;&#x5F88;&#x76F8;&#x4F3C;&#xFF0C;&#x4E5F;&#x662F;&#x5BF9;&#x6570;&#x7EC4;&#x7684;&#x6240;&#x6709;&#x6210;&#x5458;&#x4F9D;&#x6B21;&#x6267;&#x884C;&#x53C2;&#x6570;&#x51FD;&#x6570;&#x3002;&#x4F46;&#x662F;&#xFF0C;<code>forEach</code>&#x65B9;&#x6CD5;&#x4E0D;&#x8FD4;&#x56DE;&#x503C;&#xFF0C;&#x53EA;&#x7528;&#x6765;&#x64CD;&#x4F5C;&#x6570;&#x636E;&#x3002;&#x8FD9;&#x5C31;&#x662F;&#x8BF4;&#xFF0C;&#x5982;&#x679C;&#x6570;&#x7EC4;&#x904D;&#x5386;&#x7684;&#x76EE;&#x7684;&#x662F;&#x4E3A;&#x4E86;&#x5F97;&#x5230;&#x8FD4;&#x56DE;&#x503C;&#xFF0C;&#x90A3;&#x4E48;&#x4F7F;&#x7528;<code>map</code>&#x65B9;&#x6CD5;&#xFF0C;&#x5426;&#x5219;&#x4F7F;&#x7528;<code>forEach</code>&#x65B9;&#x6CD5;&#x3002;</p>
<p><code>forEach</code>&#x7684;&#x7528;&#x6CD5;&#x4E0E;<code>map</code>&#x65B9;&#x6CD5;&#x4E00;&#x81F4;&#xFF0C;&#x53C2;&#x6570;&#x662F;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#xFF0C;&#x8BE5;&#x51FD;&#x6570;&#x540C;&#x6837;&#x63A5;&#x53D7;&#x4E09;&#x4E2A;&#x53C2;&#x6570;&#xFF1A;&#x5F53;&#x524D;&#x503C;&#x3001;&#x5F53;&#x524D;&#x4F4D;&#x7F6E;&#x3001;&#x6574;&#x4E2A;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">log</span>(<span class="hljs-params">element, index, array</span>) </span>{
  <span class="hljs-built_in">console</span>.log(<span class="hljs-string">&apos;[&apos;</span> + index + <span class="hljs-string">&apos;] = &apos;</span> + element);
}

[<span class="hljs-number">2</span>, <span class="hljs-number">5</span>, <span class="hljs-number">9</span>].forEach(log);
<span class="hljs-comment">// [0] = 2</span>
<span class="hljs-comment">// [1] = 5</span>
<span class="hljs-comment">// [2] = 9</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>forEach</code>&#x904D;&#x5386;&#x6570;&#x7EC4;&#x4E0D;&#x662F;&#x4E3A;&#x4E86;&#x5F97;&#x5230;&#x8FD4;&#x56DE;&#x503C;&#xFF0C;&#x800C;&#x662F;&#x4E3A;&#x4E86;&#x5728;&#x5C4F;&#x5E55;&#x8F93;&#x51FA;&#x5185;&#x5BB9;&#xFF0C;&#x6240;&#x4EE5;&#x4E0D;&#x5FC5;&#x4F7F;&#x7528;<code>map</code>&#x65B9;&#x6CD5;&#x3002;</p>
<p><code>forEach</code>&#x65B9;&#x6CD5;&#x4E5F;&#x53EF;&#x4EE5;&#x63A5;&#x53D7;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x7ED1;&#x5B9A;&#x53C2;&#x6570;&#x51FD;&#x6570;&#x7684;<code>this</code>&#x53D8;&#x91CF;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> out = [];

[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>].forEach(<span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params">elem</span>) </span>{
  <span class="hljs-keyword">this</span>.push(elem * elem);
}, out);

out <span class="hljs-comment">// [1, 4, 9]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x7A7A;&#x6570;&#x7EC4;<code>out</code>&#x662F;<code>forEach</code>&#x65B9;&#x6CD5;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x7ED3;&#x679C;&#xFF0C;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x5185;&#x90E8;&#x7684;<code>this</code>&#x5173;&#x952E;&#x5B57;&#x5C31;&#x6307;&#x5411;<code>out</code>&#x3002;</p>
<p>&#x6CE8;&#x610F;&#xFF0C;<code>forEach</code>&#x65B9;&#x6CD5;&#x65E0;&#x6CD5;&#x4E2D;&#x65AD;&#x6267;&#x884C;&#xFF0C;&#x603B;&#x662F;&#x4F1A;&#x5C06;&#x6240;&#x6709;&#x6210;&#x5458;&#x904D;&#x5386;&#x5B8C;&#x3002;&#x5982;&#x679C;&#x5E0C;&#x671B;&#x7B26;&#x5408;&#x67D0;&#x79CD;&#x6761;&#x4EF6;&#x65F6;&#xFF0C;&#x5C31;&#x4E2D;&#x65AD;&#x904D;&#x5386;&#xFF0C;&#x8981;&#x4F7F;&#x7528;<code>for</code>&#x5FAA;&#x73AF;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>];

<span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>; i &lt; arr.length; i++) {
  <span class="hljs-keyword">if</span> (arr[i] === <span class="hljs-number">2</span>) <span class="hljs-keyword">break</span>;
  <span class="hljs-built_in">console</span>.log(arr[i]);
}
<span class="hljs-comment">// 1</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x6267;&#x884C;&#x5230;&#x6570;&#x7EC4;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x6210;&#x5458;&#x65F6;&#xFF0C;&#x5C31;&#x4F1A;&#x4E2D;&#x65AD;&#x6267;&#x884C;&#x3002;<code>forEach</code>&#x65B9;&#x6CD5;&#x505A;&#x4E0D;&#x5230;&#x8FD9;&#x4E00;&#x70B9;&#x3002;</p>
<p><code>forEach</code>&#x65B9;&#x6CD5;&#x4E5F;&#x4F1A;&#x8DF3;&#x8FC7;&#x6570;&#x7EC4;&#x7684;&#x7A7A;&#x4F4D;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> log = <span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">n</span>) </span>{
  <span class="hljs-built_in">console</span>.log(n + <span class="hljs-number">1</span>);
};

[<span class="hljs-number">1</span>, <span class="hljs-literal">undefined</span>, <span class="hljs-number">2</span>].forEach(log)
<span class="hljs-comment">// 2</span>
<span class="hljs-comment">// NaN</span>
<span class="hljs-comment">// 3</span>

[<span class="hljs-number">1</span>, <span class="hljs-literal">null</span>, <span class="hljs-number">2</span>].forEach(log)
<span class="hljs-comment">// 2</span>
<span class="hljs-comment">// 1</span>
<span class="hljs-comment">// 3</span>

[<span class="hljs-number">1</span>, , <span class="hljs-number">2</span>].forEach(log)
<span class="hljs-comment">// 2</span>
<span class="hljs-comment">// 3</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>forEach</code>&#x65B9;&#x6CD5;&#x4E0D;&#x4F1A;&#x8DF3;&#x8FC7;<code>undefined</code>&#x548C;<code>null</code>&#xFF0C;&#x4F46;&#x4F1A;&#x8DF3;&#x8FC7;&#x7A7A;&#x4F4D;&#x3002;</p>
<h3 id="filter">filter()</h3>
<p><code>filter</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x8FC7;&#x6EE4;&#x6570;&#x7EC4;&#x6210;&#x5458;&#xFF0C;&#x6EE1;&#x8DB3;&#x6761;&#x4EF6;&#x7684;&#x6210;&#x5458;&#x7EC4;&#x6210;&#x4E00;&#x4E2A;&#x65B0;&#x6570;&#x7EC4;&#x8FD4;&#x56DE;&#x3002;</p>
<p>&#x5B83;&#x7684;&#x53C2;&#x6570;&#x662F;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#xFF0C;&#x6240;&#x6709;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x4F9D;&#x6B21;&#x6267;&#x884C;&#x8BE5;&#x51FD;&#x6570;&#xFF0C;&#x8FD4;&#x56DE;&#x7ED3;&#x679C;&#x4E3A;<code>true</code>&#x7684;&#x6210;&#x5458;&#x7EC4;&#x6210;&#x4E00;&#x4E2A;&#x65B0;&#x6570;&#x7EC4;&#x8FD4;&#x56DE;&#x3002;&#x8BE5;&#x65B9;&#x6CD5;&#x4E0D;&#x4F1A;&#x6539;&#x53D8;&#x539F;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>].filter(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">elem</span>) </span>{
  <span class="hljs-keyword">return</span> (elem &gt; <span class="hljs-number">3</span>);
})
<span class="hljs-comment">// [4, 5]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x5C06;&#x5927;&#x4E8E;<code>3</code>&#x7684;&#x6570;&#x7EC4;&#x6210;&#x5458;&#xFF0C;&#x4F5C;&#x4E3A;&#x4E00;&#x4E2A;&#x65B0;&#x6570;&#x7EC4;&#x8FD4;&#x56DE;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">0</span>, <span class="hljs-number">1</span>, <span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-literal">false</span>];

arr.filter(<span class="hljs-built_in">Boolean</span>)
<span class="hljs-comment">// [1, &quot;a&quot;]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>filter</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x6570;&#x7EC4;<code>arr</code>&#x91CC;&#x9762;&#x6240;&#x6709;&#x5E03;&#x5C14;&#x503C;&#x4E3A;<code>true</code>&#x7684;&#x6210;&#x5458;&#x3002;</p>
<p><code>filter</code>&#x65B9;&#x6CD5;&#x7684;&#x53C2;&#x6570;&#x51FD;&#x6570;&#x53EF;&#x4EE5;&#x63A5;&#x53D7;&#x4E09;&#x4E2A;&#x53C2;&#x6570;&#xFF1A;&#x5F53;&#x524D;&#x6210;&#x5458;&#xFF0C;&#x5F53;&#x524D;&#x4F4D;&#x7F6E;&#x548C;&#x6574;&#x4E2A;&#x6570;&#x7EC4;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>].filter(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">elem, index, arr</span>) </span>{
  <span class="hljs-keyword">return</span> index % <span class="hljs-number">2</span> === <span class="hljs-number">0</span>;
});
<span class="hljs-comment">// [1, 3, 5]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x8FD4;&#x56DE;&#x5076;&#x6570;&#x4F4D;&#x7F6E;&#x7684;&#x6210;&#x5458;&#x7EC4;&#x6210;&#x7684;&#x65B0;&#x6570;&#x7EC4;&#x3002;</p>
<p><code>filter</code>&#x65B9;&#x6CD5;&#x8FD8;&#x53EF;&#x4EE5;&#x63A5;&#x53D7;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x7528;&#x6765;&#x7ED1;&#x5B9A;&#x53C2;&#x6570;&#x51FD;&#x6570;&#x5185;&#x90E8;&#x7684;<code>this</code>&#x53D8;&#x91CF;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> obj = { MAX: <span class="hljs-number">3</span> };
<span class="hljs-keyword">var</span> myFilter = <span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">item</span>) </span>{
  <span class="hljs-keyword">if</span> (item &gt; <span class="hljs-keyword">this</span>.MAX) <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>;
};

<span class="hljs-keyword">var</span> arr = [<span class="hljs-number">2</span>, <span class="hljs-number">8</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">1</span>, <span class="hljs-number">3</span>, <span class="hljs-number">2</span>, <span class="hljs-number">9</span>];
arr.filter(myFilter, obj) <span class="hljs-comment">// [8, 4, 9]</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x8FC7;&#x6EE4;&#x5668;<code>myFilter</code>&#x5185;&#x90E8;&#x6709;<code>this</code>&#x53D8;&#x91CF;&#xFF0C;&#x5B83;&#x53EF;&#x4EE5;&#x88AB;<code>filter</code>&#x65B9;&#x6CD5;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;<code>obj</code>&#x7ED1;&#x5B9A;&#xFF0C;&#x8FD4;&#x56DE;&#x5927;&#x4E8E;<code>3</code>&#x7684;&#x6210;&#x5458;&#x3002;</p>
<h3 id="some&#xFF0C;every">some()&#xFF0C;every()</h3>
<p>&#x8FD9;&#x4E24;&#x4E2A;&#x65B9;&#x6CD5;&#x7C7B;&#x4F3C;&#x201C;&#x65AD;&#x8A00;&#x201D;&#xFF08;assert&#xFF09;&#xFF0C;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x5E03;&#x5C14;&#x503C;&#xFF0C;&#x8868;&#x793A;&#x5224;&#x65AD;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x662F;&#x5426;&#x7B26;&#x5408;&#x67D0;&#x79CD;&#x6761;&#x4EF6;&#x3002;</p>
<p>&#x5B83;&#x4EEC;&#x63A5;&#x53D7;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#x4F5C;&#x4E3A;&#x53C2;&#x6570;&#xFF0C;&#x6240;&#x6709;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x4F9D;&#x6B21;&#x6267;&#x884C;&#x8BE5;&#x51FD;&#x6570;&#x3002;&#x8BE5;&#x51FD;&#x6570;&#x63A5;&#x53D7;&#x4E09;&#x4E2A;&#x53C2;&#x6570;&#xFF1A;&#x5F53;&#x524D;&#x6210;&#x5458;&#x3001;&#x5F53;&#x524D;&#x4F4D;&#x7F6E;&#x548C;&#x6574;&#x4E2A;&#x6570;&#x7EC4;&#xFF0C;&#x7136;&#x540E;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x5E03;&#x5C14;&#x503C;&#x3002;</p>
<p><code>some</code>&#x65B9;&#x6CD5;&#x662F;&#x53EA;&#x8981;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x662F;<code>true</code>&#xFF0C;&#x5219;&#x6574;&#x4E2A;<code>some</code>&#x65B9;&#x6CD5;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x5C31;&#x662F;<code>true</code>&#xFF0C;&#x5426;&#x5219;&#x8FD4;&#x56DE;<code>false</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>];
arr.some(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">elem, index, arr</span>) </span>{
  <span class="hljs-keyword">return</span> elem &gt;= <span class="hljs-number">3</span>;
});
<span class="hljs-comment">// true</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5982;&#x679C;&#x6570;&#x7EC4;<code>arr</code>&#x6709;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#x5927;&#x4E8E;&#x7B49;&#x4E8E;3&#xFF0C;<code>some</code>&#x65B9;&#x6CD5;&#x5C31;&#x8FD4;&#x56DE;<code>true</code>&#x3002;</p>
<p><code>every</code>&#x65B9;&#x6CD5;&#x662F;&#x6240;&#x6709;&#x6210;&#x5458;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x90FD;&#x662F;<code>true</code>&#xFF0C;&#x6574;&#x4E2A;<code>every</code>&#x65B9;&#x6CD5;&#x624D;&#x8FD4;&#x56DE;<code>true</code>&#xFF0C;&#x5426;&#x5219;&#x8FD4;&#x56DE;<code>false</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>];
arr.every(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">elem, index, arr</span>) </span>{
  <span class="hljs-keyword">return</span> elem &gt;= <span class="hljs-number">3</span>;
});
<span class="hljs-comment">// false</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x6570;&#x7EC4;<code>arr</code>&#x5E76;&#x975E;&#x6240;&#x6709;&#x6210;&#x5458;&#x5927;&#x4E8E;&#x7B49;&#x4E8E;<code>3</code>&#xFF0C;&#x6240;&#x4EE5;&#x8FD4;&#x56DE;<code>false</code>&#x3002;</p>
<p>&#x6CE8;&#x610F;&#xFF0C;&#x5BF9;&#x4E8E;&#x7A7A;&#x6570;&#x7EC4;&#xFF0C;<code>some</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;<code>false</code>&#xFF0C;<code>every</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;<code>true</code>&#xFF0C;&#x56DE;&#x8C03;&#x51FD;&#x6570;&#x90FD;&#x4E0D;&#x4F1A;&#x6267;&#x884C;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">isEven</span>(<span class="hljs-params">x</span>) </span>{ <span class="hljs-keyword">return</span> x % <span class="hljs-number">2</span> === <span class="hljs-number">0</span> }

[].some(isEven) <span class="hljs-comment">// false</span>
[].every(isEven) <span class="hljs-comment">// true</span>
</code></pre>
<p><code>some</code>&#x548C;<code>every</code>&#x65B9;&#x6CD5;&#x8FD8;&#x53EF;&#x4EE5;&#x63A5;&#x53D7;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x7528;&#x6765;&#x7ED1;&#x5B9A;&#x53C2;&#x6570;&#x51FD;&#x6570;&#x5185;&#x90E8;&#x7684;<code>this</code>&#x53D8;&#x91CF;&#x3002;</p>
<h3 id="reduce&#xFF0C;reduceright">reduce()&#xFF0C;reduceRight()</h3>
<p><code>reduce</code>&#x65B9;&#x6CD5;&#x548C;<code>reduceRight</code>&#x65B9;&#x6CD5;&#x4F9D;&#x6B21;&#x5904;&#x7406;&#x6570;&#x7EC4;&#x7684;&#x6BCF;&#x4E2A;&#x6210;&#x5458;&#xFF0C;&#x6700;&#x7EC8;&#x7D2F;&#x8BA1;&#x4E3A;&#x4E00;&#x4E2A;&#x503C;&#x3002;&#x5B83;&#x4EEC;&#x7684;&#x5DEE;&#x522B;&#x662F;&#xFF0C;<code>reduce</code>&#x662F;&#x4ECE;&#x5DE6;&#x5230;&#x53F3;&#x5904;&#x7406;&#xFF08;&#x4ECE;&#x7B2C;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#x5230;&#x6700;&#x540E;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#xFF09;&#xFF0C;<code>reduceRight</code>&#x5219;&#x662F;&#x4ECE;&#x53F3;&#x5230;&#x5DE6;&#xFF08;&#x4ECE;&#x6700;&#x540E;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#x5230;&#x7B2C;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#xFF09;&#xFF0C;&#x5176;&#x4ED6;&#x5B8C;&#x5168;&#x4E00;&#x6837;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>].reduce(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">a, b</span>) </span>{
  <span class="hljs-built_in">console</span>.log(a, b);
  <span class="hljs-keyword">return</span> a + b;
})
<span class="hljs-comment">// 1 2</span>
<span class="hljs-comment">// 3 3</span>
<span class="hljs-comment">// 6 4</span>
<span class="hljs-comment">// 10 5</span>
<span class="hljs-comment">//&#x6700;&#x540E;&#x7ED3;&#x679C;&#xFF1A;15</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>reduce</code>&#x65B9;&#x6CD5;&#x6C42;&#x51FA;&#x6570;&#x7EC4;&#x6240;&#x6709;&#x6210;&#x5458;&#x7684;&#x548C;&#x3002;&#x7B2C;&#x4E00;&#x6B21;&#x6267;&#x884C;&#xFF0C;<code>a</code>&#x662F;&#x6570;&#x7EC4;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x6210;&#x5458;<code>1</code>&#xFF0C;<code>b</code>&#x662F;&#x6570;&#x7EC4;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x6210;&#x5458;<code>2</code>&#x3002;&#x7B2C;&#x4E8C;&#x6B21;&#x6267;&#x884C;&#xFF0C;<code>a</code>&#x4E3A;&#x4E0A;&#x4E00;&#x8F6E;&#x7684;&#x8FD4;&#x56DE;&#x503C;<code>3</code>&#xFF0C;<code>b</code>&#x4E3A;&#x7B2C;&#x4E09;&#x4E2A;&#x6210;&#x5458;<code>3</code>&#x3002;&#x7B2C;&#x4E09;&#x6B21;&#x6267;&#x884C;&#xFF0C;<code>a</code>&#x4E3A;&#x4E0A;&#x4E00;&#x8F6E;&#x7684;&#x8FD4;&#x56DE;&#x503C;<code>6</code>&#xFF0C;<code>b</code>&#x4E3A;&#x7B2C;&#x56DB;&#x4E2A;&#x6210;&#x5458;<code>4</code>&#x3002;&#x7B2C;&#x56DB;&#x6B21;&#x6267;&#x884C;&#xFF0C;<code>a</code>&#x4E3A;&#x4E0A;&#x4E00;&#x8F6E;&#x8FD4;&#x56DE;&#x503C;<code>10</code>&#xFF0C;<code>b</code>&#x4E3A;&#x7B2C;&#x4E94;&#x4E2A;&#x6210;&#x5458;<code>5</code>&#x3002;&#x81F3;&#x6B64;&#x6240;&#x6709;&#x6210;&#x5458;&#x904D;&#x5386;&#x5B8C;&#x6210;&#xFF0C;&#x6574;&#x4E2A;&#x65B9;&#x6CD5;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x5C31;&#x662F;&#x6700;&#x540E;&#x4E00;&#x8F6E;&#x7684;&#x8FD4;&#x56DE;&#x503C;<code>15</code>&#x3002;</p>
<p><code>reduce</code>&#x65B9;&#x6CD5;&#x548C;<code>reduceRight</code>&#x65B9;&#x6CD5;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x90FD;&#x662F;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#x3002;&#x8BE5;&#x51FD;&#x6570;&#x63A5;&#x53D7;&#x4EE5;&#x4E0B;&#x56DB;&#x4E2A;&#x53C2;&#x6570;&#x3002;</p>
<ol>
<li>&#x7D2F;&#x79EF;&#x53D8;&#x91CF;&#xFF0C;&#x9ED8;&#x8BA4;&#x4E3A;&#x6570;&#x7EC4;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x6210;&#x5458;</li>
<li>&#x5F53;&#x524D;&#x53D8;&#x91CF;&#xFF0C;&#x9ED8;&#x8BA4;&#x4E3A;&#x6570;&#x7EC4;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x6210;&#x5458;</li>
<li>&#x5F53;&#x524D;&#x4F4D;&#x7F6E;&#xFF08;&#x4ECE;0&#x5F00;&#x59CB;&#xFF09;</li>
<li>&#x539F;&#x6570;&#x7EC4;</li>
</ol>
<p>&#x8FD9;&#x56DB;&#x4E2A;&#x53C2;&#x6570;&#x4E4B;&#x4E2D;&#xFF0C;&#x53EA;&#x6709;&#x524D;&#x4E24;&#x4E2A;&#x662F;&#x5FC5;&#x987B;&#x7684;&#xFF0C;&#x540E;&#x4E24;&#x4E2A;&#x5219;&#x662F;&#x53EF;&#x9009;&#x7684;&#x3002;</p>
<p>&#x5982;&#x679C;&#x8981;&#x5BF9;&#x7D2F;&#x79EF;&#x53D8;&#x91CF;&#x6307;&#x5B9A;&#x521D;&#x503C;&#xFF0C;&#x53EF;&#x4EE5;&#x628A;&#x5B83;&#x653E;&#x5728;<code>reduce</code>&#x65B9;&#x6CD5;&#x548C;<code>reduceRight</code>&#x65B9;&#x6CD5;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>].reduce(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">a, b</span>) </span>{
  <span class="hljs-keyword">return</span> a + b;
}, <span class="hljs-number">10</span>);
<span class="hljs-comment">// 25</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x6307;&#x5B9A;&#x53C2;&#x6570;<code>a</code>&#x7684;&#x521D;&#x503C;&#x4E3A;10&#xFF0C;&#x6240;&#x4EE5;&#x6570;&#x7EC4;&#x4ECE;10&#x5F00;&#x59CB;&#x7D2F;&#x52A0;&#xFF0C;&#x6700;&#x7EC8;&#x7ED3;&#x679C;&#x4E3A;25&#x3002;&#x6CE8;&#x610F;&#xFF0C;&#x8FD9;&#x65F6;<code>b</code>&#x662F;&#x4ECE;&#x6570;&#x7EC4;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x6210;&#x5458;&#x5F00;&#x59CB;&#x904D;&#x5386;&#x3002;</p>
<p>&#x4E0A;&#x9762;&#x7684;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x76F8;&#x5F53;&#x4E8E;&#x8BBE;&#x5B9A;&#x4E86;&#x9ED8;&#x8BA4;&#x503C;&#xFF0C;&#x5904;&#x7406;&#x7A7A;&#x6570;&#x7EC4;&#x65F6;&#x5C24;&#x5176;&#x6709;&#x7528;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">add</span>(<span class="hljs-params">prev, cur</span>) </span>{
  <span class="hljs-keyword">return</span> prev + cur;
}

[].reduce(add)
<span class="hljs-comment">// TypeError: Reduce of empty array with no initial value</span>
[].reduce(add, <span class="hljs-number">1</span>)
<span class="hljs-comment">// 1</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x7531;&#x4E8E;&#x7A7A;&#x6570;&#x7EC4;&#x53D6;&#x4E0D;&#x5230;&#x521D;&#x59CB;&#x503C;&#xFF0C;<code>reduce</code>&#x65B9;&#x6CD5;&#x4F1A;&#x62A5;&#x9519;&#x3002;&#x8FD9;&#x65F6;&#xFF0C;&#x52A0;&#x4E0A;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x5C31;&#x80FD;&#x4FDD;&#x8BC1;&#x603B;&#x662F;&#x4F1A;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x503C;&#x3002;</p>
<p>&#x4E0B;&#x9762;&#x662F;&#x4E00;&#x4E2A;<code>reduceRight</code>&#x65B9;&#x6CD5;&#x7684;&#x4F8B;&#x5B50;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">subtract</span>(<span class="hljs-params">prev, cur</span>) </span>{
  <span class="hljs-keyword">return</span> prev - cur;
}

[<span class="hljs-number">3</span>, <span class="hljs-number">2</span>, <span class="hljs-number">1</span>].reduce(subtract) <span class="hljs-comment">// 0</span>
[<span class="hljs-number">3</span>, <span class="hljs-number">2</span>, <span class="hljs-number">1</span>].reduceRight(subtract) <span class="hljs-comment">// -4</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>reduce</code>&#x65B9;&#x6CD5;&#x76F8;&#x5F53;&#x4E8E;<code>3</code>&#x51CF;&#x53BB;<code>2</code>&#x518D;&#x51CF;&#x53BB;<code>1</code>&#xFF0C;<code>reduceRight</code>&#x65B9;&#x6CD5;&#x76F8;&#x5F53;&#x4E8E;<code>1</code>&#x51CF;&#x53BB;<code>2</code>&#x518D;&#x51CF;&#x53BB;<code>3</code>&#x3002;</p>
<p>&#x7531;&#x4E8E;&#x8FD9;&#x4E24;&#x4E2A;&#x65B9;&#x6CD5;&#x4F1A;&#x904D;&#x5386;&#x6570;&#x7EC4;&#xFF0C;&#x6240;&#x4EE5;&#x5B9E;&#x9645;&#x4E0A;&#x8FD8;&#x53EF;&#x4EE5;&#x7528;&#x6765;&#x505A;&#x4E00;&#x4E9B;&#x904D;&#x5386;&#x76F8;&#x5173;&#x7684;&#x64CD;&#x4F5C;&#x3002;&#x6BD4;&#x5982;&#xFF0C;&#x627E;&#x51FA;&#x5B57;&#x7B26;&#x957F;&#x5EA6;&#x6700;&#x957F;&#x7684;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">findLongest</span>(<span class="hljs-params">entries</span>) </span>{
  <span class="hljs-keyword">return</span> entries.reduce(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">longest, entry</span>) </span>{
    <span class="hljs-keyword">return</span> entry.length &gt; longest.length ? entry : longest;
  }, <span class="hljs-string">&apos;&apos;</span>);
}

findLongest([<span class="hljs-string">&apos;aaa&apos;</span>, <span class="hljs-string">&apos;bb&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>]) <span class="hljs-comment">// &quot;aaa&quot;</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>reduce</code>&#x7684;&#x53C2;&#x6570;&#x51FD;&#x6570;&#x4F1A;&#x5C06;&#x5B57;&#x7B26;&#x957F;&#x5EA6;&#x8F83;&#x957F;&#x7684;&#x90A3;&#x4E2A;&#x6570;&#x7EC4;&#x6210;&#x5458;&#xFF0C;&#x4F5C;&#x4E3A;&#x7D2F;&#x79EF;&#x503C;&#x3002;&#x8FD9;&#x5BFC;&#x81F4;&#x904D;&#x5386;&#x6240;&#x6709;&#x6210;&#x5458;&#x4E4B;&#x540E;&#xFF0C;&#x7D2F;&#x79EF;&#x503C;&#x5C31;&#x662F;&#x5B57;&#x7B26;&#x957F;&#x5EA6;&#x6700;&#x957F;&#x7684;&#x90A3;&#x4E2A;&#x6210;&#x5458;&#x3002;</p>
<h3 id="indexof&#xFF0C;lastindexof">indexOf()&#xFF0C;lastIndexOf()</h3>
<p><code>indexOf</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x7ED9;&#x5B9A;&#x5143;&#x7D20;&#x5728;&#x6570;&#x7EC4;&#x4E2D;&#x7B2C;&#x4E00;&#x6B21;&#x51FA;&#x73B0;&#x7684;&#x4F4D;&#x7F6E;&#xFF0C;&#x5982;&#x679C;&#x6CA1;&#x6709;&#x51FA;&#x73B0;&#x5219;&#x8FD4;&#x56DE;<code>-1</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>];

a.indexOf(<span class="hljs-string">&apos;b&apos;</span>) <span class="hljs-comment">// 1</span>
a.indexOf(<span class="hljs-string">&apos;y&apos;</span>) <span class="hljs-comment">// -1</span>
</code></pre>
<p><code>indexOf</code>&#x65B9;&#x6CD5;&#x8FD8;&#x53EF;&#x4EE5;&#x63A5;&#x53D7;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#xFF0C;&#x8868;&#x793A;&#x641C;&#x7D22;&#x7684;&#x5F00;&#x59CB;&#x4F4D;&#x7F6E;&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-string">&apos;b&apos;</span>, <span class="hljs-string">&apos;c&apos;</span>].indexOf(<span class="hljs-string">&apos;a&apos;</span>, <span class="hljs-number">1</span>) <span class="hljs-comment">// -1</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4ECE;1&#x53F7;&#x4F4D;&#x7F6E;&#x5F00;&#x59CB;&#x641C;&#x7D22;&#x5B57;&#x7B26;<code>a</code>&#xFF0C;&#x7ED3;&#x679C;&#x4E3A;<code>-1</code>&#xFF0C;&#x8868;&#x793A;&#x6CA1;&#x6709;&#x641C;&#x7D22;&#x5230;&#x3002;</p>
<p><code>lastIndexOf</code>&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x7ED9;&#x5B9A;&#x5143;&#x7D20;&#x5728;&#x6570;&#x7EC4;&#x4E2D;&#x6700;&#x540E;&#x4E00;&#x6B21;&#x51FA;&#x73B0;&#x7684;&#x4F4D;&#x7F6E;&#xFF0C;&#x5982;&#x679C;&#x6CA1;&#x6709;&#x51FA;&#x73B0;&#x5219;&#x8FD4;&#x56DE;<code>-1</code>&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> a = [<span class="hljs-number">2</span>, <span class="hljs-number">5</span>, <span class="hljs-number">9</span>, <span class="hljs-number">2</span>];
a.lastIndexOf(<span class="hljs-number">2</span>) <span class="hljs-comment">// 3</span>
a.lastIndexOf(<span class="hljs-number">7</span>) <span class="hljs-comment">// -1</span>
</code></pre>
<p>&#x6CE8;&#x610F;&#xFF0C;&#x8FD9;&#x4E24;&#x4E2A;&#x65B9;&#x6CD5;&#x4E0D;&#x80FD;&#x7528;&#x6765;&#x641C;&#x7D22;<code>NaN</code>&#x7684;&#x4F4D;&#x7F6E;&#xFF0C;&#x5373;&#x5B83;&#x4EEC;&#x65E0;&#x6CD5;&#x786E;&#x5B9A;&#x6570;&#x7EC4;&#x6210;&#x5458;&#x662F;&#x5426;&#x5305;&#x542B;<code>NaN</code>&#x3002;</p>
<pre><code class="lang-javascript">[<span class="hljs-literal">NaN</span>].indexOf(<span class="hljs-literal">NaN</span>) <span class="hljs-comment">// -1</span>
[<span class="hljs-literal">NaN</span>].lastIndexOf(<span class="hljs-literal">NaN</span>) <span class="hljs-comment">// -1</span>
</code></pre>
<p>&#x8FD9;&#x662F;&#x56E0;&#x4E3A;&#x8FD9;&#x4E24;&#x4E2A;&#x65B9;&#x6CD5;&#x5185;&#x90E8;&#xFF0C;&#x4F7F;&#x7528;&#x4E25;&#x683C;&#x76F8;&#x7B49;&#x8FD0;&#x7B97;&#x7B26;&#xFF08;<code>===</code>&#xFF09;&#x8FDB;&#x884C;&#x6BD4;&#x8F83;&#xFF0C;&#x800C;<code>NaN</code>&#x662F;&#x552F;&#x4E00;&#x4E00;&#x4E2A;&#x4E0D;&#x7B49;&#x4E8E;&#x81EA;&#x8EAB;&#x7684;&#x503C;&#x3002;</p>
<h3 id="&#x94FE;&#x5F0F;&#x4F7F;&#x7528;">&#x94FE;&#x5F0F;&#x4F7F;&#x7528;</h3>
<p>&#x4E0A;&#x9762;&#x8FD9;&#x4E9B;&#x6570;&#x7EC4;&#x65B9;&#x6CD5;&#x4E4B;&#x4E2D;&#xFF0C;&#x6709;&#x4E0D;&#x5C11;&#x8FD4;&#x56DE;&#x7684;&#x8FD8;&#x662F;&#x6570;&#x7EC4;&#xFF0C;&#x6240;&#x4EE5;&#x53EF;&#x4EE5;&#x94FE;&#x5F0F;&#x4F7F;&#x7528;&#x3002;</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> users = [
  {name: <span class="hljs-string">&apos;tom&apos;</span>, email: <span class="hljs-string">&apos;tom@example.com&apos;</span>},
  {name: <span class="hljs-string">&apos;peter&apos;</span>, email: <span class="hljs-string">&apos;peter@example.com&apos;</span>}
];

users
.map(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">user</span>) </span>{
  <span class="hljs-keyword">return</span> user.email;
})
.filter(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">email</span>) </span>{
  <span class="hljs-keyword">return</span> <span class="hljs-regexp">/^t/</span>.test(email);
})
.forEach(<span class="hljs-function"><span class="hljs-keyword">function</span> (<span class="hljs-params">email</span>) </span>{
  <span class="hljs-built_in">console</span>.log(email);
});
<span class="hljs-comment">// &quot;tom@example.com&quot;</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5148;&#x4EA7;&#x751F;&#x4E00;&#x4E2A;&#x6240;&#x6709; Email &#x5730;&#x5740;&#x7EC4;&#x6210;&#x7684;&#x6570;&#x7EC4;&#xFF0C;&#x7136;&#x540E;&#x518D;&#x8FC7;&#x6EE4;&#x51FA;&#x4EE5;<code>t</code>&#x5F00;&#x5934;&#x7684; Email &#x5730;&#x5740;&#xFF0C;&#x6700;&#x540E;&#x5C06;&#x5B83;&#x6253;&#x5370;&#x51FA;&#x6765;&#x3002;</p>
<h2 id="&#x53C2;&#x8003;&#x94FE;&#x63A5;">&#x53C2;&#x8003;&#x94FE;&#x63A5;</h2>
<ul>
<li>Nicolas Bevacqua, <a href="http://flippinawesome.org/2013/11/25/fun-with-javascript-native-array-functions/" target="_blank" rel="nofollow">Fun with JavaScript Native Array Functions</a></li>
</ul>




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